Many components are assembled to the front end of a vehicle that require precise alignment and durable mounting mechanisms. Headlights, parking lights, a decorative grill and a radiator are parts that may be attached directly or indirectly to a grill opening reinforcement. Grill opening reinforcements have been found to be helpful in tying together such components with the forward section of front fenders and the frame of a vehicle as it is being assembled.
Other integrated front end modules that support other parts include bumper reinforcements, radiator supports, and inner fender reinforcements. These parts are relatively large and must maintain close tolerances for critical dimensions to meet strict fit and finish standards.
Grill opening reinforcements and other integrated front end modules have traditionally been manufactured from a plurality of sheet metal stampings that are either welded or fastened together. Metal integrated front end modules are heavy and add to the overall vehicle weight. Being formed in multiple pieces, metal integrated front end modules require labor intensive assembly operations. Quality control is required to assure proper location of the mounting mechanisms for multiple parts assembled to the integrated front end module.
Recently, sheet molding compound (SMC) has been used to manufacture grill opening reinforcements. SMC grill opening reinforcements are generally slightly less weight than metal grill opening reinforcements. SMC grill opening reinforcements require a substantial investment in tooling for both molding the SMC and finishing the SMC parts after molding. It is generally necessary to machine a SMC grill opening reinforcement by drilling, punching or shaping with a router fastener holes and locating surfaces. Also, the SMC process is relatively slow requiring a large number of mold cavities to manufacture parts on a production basis. SMC is also not a recyclable material which means that at the end of the car's life cycle or if there is any scrap in manufacturing process, it is necessary to dispose of the SMC grill opening reinforcement in landfill instead of recycling.
It is believed that prior art attempts have been made to injection mold structural parts for vehicles. In normal vehicle assembly operations, vehicle subassemblies are subject to electro-coating at temperatures in excess of 450.degree. F. and after painting vehicle subassemblies are cycled through paint drying ovens where they are exposed to temperatures in excess of 200.degree. F. Prior attempts to utilize injection molded thermoplastic parts that are attached to automobile vehicle bodies prior to electro-coating and paint drying oven exposure have been unsuccessful when attempted with large parts such as grill opening reinforcements and other large integrated modules. Exposure of large weight bearing parts to high temperatures results in a loss of dimensional stability since the weight of parts attached to injection molded parts causes the injection molded parts to sag. This results in poor fit and finish and difficulties in assembling components after being exposed to high temperatures.
These and other disadvantages and problems encountered by the prior art are addressed by the present invention as summarized below.